Hepatic UDP-glucose 13C isotopomers from [U-13C]glucose: a simple analysis by 13C NMR of urinary menthol glucuronide.

Menthol glucuronide was isolated from the urine of a healthy 70-kg female subject following ingestion of 400 mg of peppermint oil and 6 g of 99% [U-(13)C]glucose. Glucuronide (13)C-excess enrichment levels were 4-6% and thus provided high signal-to-noise ratios (SNRs) for confident assignment of (13)C-(13)C spin-coupled multiplet components within each (13)C resonance by (13)C NMR. The [U-(13)C]glucuronide isotopomer derived via direct pathway conversion of [U-(13)C]glucose to [U-(13)C]UDP-glucose was resolved from [1,2,3-(13)C(3)]- and [1,2-(13)C(2)]glucuronide isotopomers derived via Cori cycle or indirect pathway metabolism of [U-(13)C]glucose. In a second study, a group of four overnight-fasted patients (63 +/- 10 kg) with severe heart failure were given peppermint oil and infused with [U-(13)C]glucose for 4 hr (14 mg/kg prime, 0.12 mg/kg/min constant infusion) resulting in a steady-state plasma [U-(13)C]glucose enrichment of 4.6% +/- 0.6%. Menthol glucuronide was harvested and glucuronide (13)C-isotopomers were analyzed by (13)C NMR. [U-(13)C]glucuronide enrichment was 0.6% +/- 0.1%, and the sum of [1,2,3-(13)C(3)] and [1,2-(13)C(2)]glucuronide enrichments was 0.9% +/- 0.2%. From these data, flux of plasma glucose to hepatic UDPG was estimated to be 15% +/- 4% that of endogenous glucose production (EGP), and the Cori cycle accounted for at least 32% +/- 10% of GP.     

The 12‐Lead ECG in Patients with Mahaim Fibers

The aim of this review article is to discuss the electrocardiographic presentation of the so called variants of pre‐excitation (“Mahaim fibers”) during sinus rhythm and tachycardia.     

旁道位置与室上性心动过速首次发作时年龄及性别的关系探讨

目的为了解旁道位置与室上性心动过速初次发作时年龄及性别的关系.方法对128例已进行过射频消融的患者进行了回顾性分析.结果男性左侧旁道发病时平均年龄大于右侧及中隔旁道平均为14岁和9岁;大于女性左侧旁道7岁,男性显性旁道发病时平均年龄小于隐匿性旁道7岁.而女性显性旁道与隐匿性旁道、左侧旁道与右侧旁道发病时平均年龄无显著性差异.结论旁道位置与室上速初次发作时年龄及性别有关.     

Signal-to-noise ratio effects in quantitative cerebral perfusion using dynamic susceptibility contrast agents.

Theoretical and simulation evidence is presented in support of the idea that the optimal manner of determining blood flow from MR perfusion studies is not necessarily obtained by setting experimental conditions to maximize either the arterial input or the measured tissue concentration level for a particular echo time (TE). The noise power in the contrast concentration curve is associated with its peak because of the nonlinear relationship between the contrast concentration and MR signal intensity curves. The optimum signal-to-noise ratio (SNR), SNR(C), for a particular contrast concentration curve can be obtained when the experimental concentration level and TE are adjusted to produce an MR intensity curve whose signal loss is 63% of the precontrast MR signal intensity. It is demonstrated that the stability of the singular valued decomposition (SVD) deconvolution approach to determine blood flow parameters is increased when the tissue curve maximum signal loss is in the range of 40-80%. The accuracy and stability of the SVD-determined blood flow parameters are affected by deviations from these optimum conditions in a manner that depends on the mean transit time (MTT) associated with the residue function. It is recommended that the experimental TE value be set so that neither the tissue nor the arterial curves are placed a region of rapidly deteriorating SNR(C).     

Radiofrequency Catheter Ablation of the Anterosuperior and Posteroinferior Atrial Approaches to the AV Node for Treatment of AV Nodal Reentrant Tachycardia

Catheter Ablation Techniques in AVNRT. Radiofrequency catheter ablation has been established as a first-line curative treatment modality in patients with symptomatic AV nodal reentrant tachycardia (AVNRT). The successful sites of stepwise catheter ablation approaches of the so-called fast and slow pathways strongly suggest that AVNRT involves the atrial approaches to the AV node. The typical fast pathway ablation sites are located anterosuperior toward the apex of the triangle of Koch, which also contains the compact AV node, whereas the usual slow pathway ablation sites are located posteroinferior toward the base of the triangle of Koch at a greater distance to the compact AV node and bundle of His. Accordingly, ablation studies with large patient cohorts have demonstrated that fast pathway ablation carries a higher risk of inadvertent complete AV block. Thus, the slow pathway is clearly the primary target site, and fast pathway ablation is rarely necessary. Different approaches for slow pathway ablation have been elaborated: anatomically oriented stepwise techniques, ablation guided by double potentials recorded within the area of the slow pathway insertion, and combined techniques. The modern concept of AVNRT suggests that this arrhythmia involves the highly complex three-dimensional nonuniform anisotropic AV junctional area. Accordingly, mapping and ablation studies demonstrated that the anterior approach is not identical with fast pathway ablation, and the posterior approach is not identical with slow pathway ablation. Therefore, it is essential for interventional electrophysiologists to familiarize themsdves with the anatomic and electrophysiologic details of this complex and variable specialized AV junctional region. In this review, the anatomic and pathophysiologic aspects of the AV junctional area as they relate to interventional therapy are summarized briefly, and the catheter techniques for ablation of the so-called fast and slow AV nodal pathways for the treatment of AVNRT are described.     

血清补体系统在流行性出血热患者中的变化及其意义

应用单向免疫扩散法测定了流行性出血热(EHF)患者的7种补体成份和血浆素原(Pg).结果表明,CT脂酶抑制剂在少尿期、多尿期和恢复期均高于正常(P<0.01);补体C_1q在多尿期高于正常(P<0.01);补体C_4在发热期和少尿期低于正常(P<0.01),以后逐渐恢复正常;补体C_3,C_5和C_9的变化与C_4相似;B因子在少尿期低于正常(P<0.01),在多尿期高于正常(P<0.05);Pg始终高于正常水平但在少尿期有回降.说明EHF患者不仅有补体经典途径的识别阶段、活化阶段和膜攻击阶段的变化,而且亦有旁路激活,其活化程度与病情有关.     

人工心瓣膜患者微栓子信号和凝血活性的相关性研究

目的 :研究人工心瓣膜患者脑动脉微栓子信号 (MES)的数量及相对强度与凝血活性的相关性。方法 :采用双门深经颅多普勒 (TCD)检测人工心瓣膜患者脑动脉MES ,同时检测患者凝血酶原时间国际通用比值 (INR) ,观察MES数量及相对强度与INR的相关性。结果 :MES阳性发现率 83 33% (2 5 30 ) ,MES出现频率 0～ 4 0 4 (中位数 4 0 )个 h ,MES平均相对强度 11～ 38(2 3 6 3±5 13)dB。INR1 12～ 3 5 1(1 95± 0 6 9)。MES数量及相对强度与INR无相关性。结论 :人工心瓣膜患者脑动脉MES与凝血活性无关 ,提示微栓子物质不是血栓性的     

多复指数模型及其在EEG数据分析中的应用

由头皮上电极所记录下的EEG信号是大脑中各种电活动,尤其是神经元电活动,互相耦合而产生的电位变化的整体反映。有一种看法认为,表面看来随机、无规则的EEG信号,实际上它的变化只是由少量几个动力学参量控制着的非线性过程。根据这个假定,我们提出使用多复指数(MCE)模型来描述EEG信号的想法。文中首先简要地介绍了用来估计时序信号MCE模型参数的非调和Fourier展开算法(NHFE)的基本思想。然后,对一个叠加有白噪声、具有4个频率成分的模拟信号,用NHFE算法估计出其MCE模型参数,并把所得的结果与用经典的周期图谱分析方法、AR模型谱分析方法所得到的信号频谱作了比较。结果表明,在SNR高的条件下,NHFE算法所估计出的模型参数能更客观地反映信号的固有特性。基于目前的有关EEG形成的假设,应用MCE模型来描述EEG将更能反映出其特征。因此,我们对MCE模型及其参数在EEG数据分析中的几种可能应用作了初步尝试。这些应用包括:EEG信号段(或一段诱发电位,或一段事件关联电位)的特征参数的提取,这些特征参数包括优势频率值、独立的频率成分个数、幅度值、正负衰减指数的个数、频带宽度与幅度乘积(能量);EEG的频率调制特性的粗略描述等。从而看到了用通常信号分析方法所看不到的EEG信号中所反映的大脑活动的变化。由于用MCE模型及其参数来描述EEG的方法更符合目前关于大脑非线性动力学行为的假设,所以这一方法将是表示EEG信号的有效途径之一。另外,MCE模型方法在EEG信号的模拟研究与数据压缩等方面也将是有用的。文中还讨论了NHFE算法应用中的一些问题。     

卒中临床路径实施概述

文章介绍和总结了国外目前卒中临床路径实施的概况，包括临床路径的简介、卒中临床路径的模式、实施效果（优点及存在的问题）以及卒中临床路径的制订。